I've always kept my basses tuned to pitch in their cases standing upright when not in use with no problems ( acoustic, electric guitars and Chapman sticks also) no matter what season it was, the temp in my house stays pretty consistant............ although about a year or more ago I went to change the strings on my Conklin 7 string bass I noticed the frets on both sides of the neck popping out and a split starting to run up the fingerboard in between the D and G strings about 6 inches long, It freaked me out cause of all the years playing, different types of instruments i've owned , and having another Conklin 7 that was older and kept in the same spot ( that nothing happened to) , I was like how the hell did that happen ? I'd never seen that happen before
I bought one of the Planet Waves large instrument humidifiers and put it in the case and in a few days the frets were back to normal and the split completely disappeared and hasn't come back since, boy was I relieved.
